Wireless communication method and apparatus thereof

ABSTRACT

To provide a stable high speed wireless network, the relay process is solved at the lower layers (PHY layer, MAC layer) without depending on upper layers to reduce the load of the upper layers to the utmost. Discrimination is made between a packet of one&#39;s own station and a relay packet to process the presence and absence of the relay packet without using a CPU to construct a wireless network executing the relay processing at a high speed. Further, the retransmission is executed without using a CPU to provide a stable wireless network. In addition, the table for relay process (routing table) is constantly updated to add to the table the information of the packets of which processes are not executed to eventually suppress unnecessary processes.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/912,943, filed Jun. 7, 2013, which is a continuation of U.S. patentapplication Ser. No. 12/813,247, filed Jun. 10, 2010, Now U.S. Pat. No.8,477,783, which is a continuation of U.S. patent application Ser. No.10/868,788 filed Jun. 17, 2004, Now U.S. Pat. No. 7,769,012, whichclaims priority under 35 U.S.C. 119 to Japanese Application No.2003-177284 filed Jun. 20, 2003, the entire contents of each of whichare incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

A preferred embodiment of the present invention relates to a wirelesscommunication method useable in application for connecting a pluralityof wireless communication networks for transmitting various types ofdata and a wireless communication apparatus used for the connection tothe communication network.

2. Related Art

To access home pages on the Internet, carry out electronic mail datatransmission, moving picture transfer and the like, communication meanshave been realized utilizing a variety of methods of communication, ascommunication means for providing connection for a terminal apparatusesto execute those data processes. For example, as a relatively high speedcommunication means, the use of ADSL (Asymmetric Digital SubscriberLine), e cable television, and optical cables have been proposed andactually practiced.

The ADSL is a communication network provided for accessing the Internetby multiplexing digital data on existent analog telephone lines. If acable television is used, it constitutes a communication network foraccessing the Internet using a vacant bandwidth in the cable preparedfor cable television sets. An optical cable is a communication networkfor accessing the Internet using an optical cable line that has beenalready installed.

There can be a case in which a special terminal apparatus is used forthe Internet connection as a terminal apparatus connected to such acommunication network in addition to the use of a personal computer.However, in any case, it is a rare case that a communication portcapable of connection to these communication networks is directlyprovided to the terminal apparatus to provide the connection. Ingeneral, a port of general-purpose such as USB (Universal Serial Bus) isprovided to a communication apparatus to be connected to thesecommunication networks, and is the apparatus is connected to computersvia the general port.

Alternatively, those for providing connection between the communicationapparatus coupled to a communication network and a computer apparatus orthe like are becoming increasingly popular. As a wireless communicationnetwork of such kind, for example, a standard called Bluetooth(Bluetooth: trade mark), a standard called IEEE (The Institute ofElectrical and Electronics Engineers) 802.11, wireless 1394 and the likehave been developed and adopted in practice. In the IEEE802.11 standard,there are various wireless communication standards such as the IEEE802.11a standard, the IEEE802.11b standard, and the like, depending onthe wireless communication method, and the used frequency bandwidth.Further, a standard called UWB (Ultra Wide Band) has been also drawingattention.

SUMMARY OF THE INVENTION

FIG. 7 is a schematic diagram illustrating a structural exampleincluding a base station and a terminal station used in such a wirelesscommunication network. This constitutes a structural example of the basestation and the terminal that uses the IEEE802.11a standard in awireless communication network and uses an OFDM (Orthogonal FrequencyDivision Multiplex) which is a multi-carrier method transmitting aplurality of sub-carriers in one transmission channel. A structure isillustrated in which the terminal station 30 receives the signaltransmitted from the base station 10.

The base station 10 is provided with a central control unit (CPU) 11that executes the control at layers higher than the network layer forthe wireless communication. A transmission timing control section 12 iscoupled to the central control unit 11. The transmission timing controlsection (time base controller) 12 executes notifying various processingsections about the type of a data transmission rate and the control oftransmission timing based on the control of the central control unit 11.In addition, it can also generate an instruction for changing the datatransmission rate. The data transmission rate can be changed, forexample, by changing the modulation method or the coding rate.

A memory 13 for storing data inputted from the outside is coupled to thecentral control unit 11 and supplies the transmission data stored in thememory 13 to a transmission data processing section 14. The transmissiondata processing section 14 is a circuit for executing the MAC (MediaAccess Control) processing. More specifically, it processes any datasuch as non-reversible coded image data including the JPEG (JointPhotographic Experts Group), the MPEG (Moving Picture coding ExpertsGroup) or the like, and reversible coded image data including JBIG(Joint Bi-level Image coding experts Group) or the like as packet typedata. Further it may also execute the process of adding error correctioncodes using Reed Solomon coding or turbo-coding.

Packet data obtained at transmission data processing section 14 issubject to inter-string distance extension at convolution section 15.The transmission-coded bit strings obtained at the convolution section15 is supplied to an interleaver 16 to interleave the coded bit stringsto disperse the bit stings. The dispersed bit strings are supplied to amodulation section 17 to insert a preamble signal into the bit strings,and then, the QPSK (Quadrature Phase Shift Keying) modulation as aprimary modulation is carried out. Here, modulation methods such as theBPSK, 8PSK, QAM (regardless of absolute and differential modulations)can be executed other than the QPSK.

The transmission symbol stream modulated by the modulation section 17 issupplied to an inverse fast Fourier transform section 18, which executesan inverse fast Fourier transform process, and further executes a windowprocess. The processing at the inverse fast Fourier transform section 18averages on time axis the transmission symbol stream imaginarilyarranged on a frequency axis.

The transmission symbols obtained by this inverse Fourier transformsection 18 is supplied to a digital•analog converter 19 to convert itinto an analog signal. The converted analog signal is supplied to an RFsection 20 to execute analog processes such as filtering, frequencyconverting or the like to wirelessly transmit the frequency-convertedsignal through the antenna 21 connected thereto.

The circuits from the transmission data processing section 14 to the RFsection 20 are subjected to setting such as the transmission timing andthe modulation method in accordance with the instruction from thetransmission timing control section 12.

Next, a reception structure of the terminal station 30 will bedescribed. At the terminal station 30, an antenna 31 is coupled to an RFsection 32, which executes analog processes such as filtering, frequencyconversion or the like of the reception signal. The reception signalprocessed at the RF section 32 is supplied to an analog/digitalconverter 33, which converts it into a digital reception symbol steam.The digital reception symbol stream is supplied to a window detectionsection 34, which executes a synchronous detection process for detectinggaps between pieces of data or frames subjected to be the fast Fouriertransform, which is an inverse process of the inverse fast Fouriertransform at event of transmission

The signal subjected to Fourier transform by the fast Fourier transformsection 35 is supplied to a demodulation section 36 that executes thedemodulation process corresponding to the modulation method used ontransmission such as the QPSK demodulation to generate a receptionsymbol stream. The generated reception symbol stream is supplied to ade-interleaver 37 that rearranges the dispersed bit strings to generatereception coded bit strings. The reception coded bit strings aresupplied to a Viterbi decoder 38 to carry out Viterbi decoding fordemodulation to have reception information bit strings, which aresupplied to a reception data processing section 39.

The reception data processing section 39 carries out the processextracting necessary data from the reception packet supplied asreception information bit strings and the error correction process basedon the error correction codes, if necessary, to supply the processeddata to the memory 40.

The central control unit 41 of the terminal station 30 outputs separatedvarious types of data such as data for respective applications and imagedata from the reception data stored in the memory 40. Further, thecentral control unit 41 is coupled to a reception timing control section42, which instructs about reception timings, signal processing methodsor the like at respective circuits based on the control of the centralcontrol unit 41.

This processing structure provides a preferable high speed datatransmission by wireless transmission between the base station 10 andthe terminal station 30. In other words, the wireless transmission bythe OFDM modulation averages the bit strings arranged on the sub-carrierin time base and provides an advantageous effect to withstandinterference waves such as fading, shadowing, or multipath. In theIEEE802.11a standard, a data transmission rate up to 54 Mps in maximumcan be set, so that it can provide data communication at a considerablyhigh data transmission rate than that of 11 Mbps according to the IEEE802.11b standard.

As various wireless standards have been described such as theIEEE802.11a standard, the IEEE802.11b standard, the Bluetooth, and theIEEE802.11g and the UWB now standardized in the above-describedstructures, they have different applications for users because thesestandards have different frequency bandwidths or data transmissionrates. The IEEE802.11b standard and the IEEE802.11g standard, havingdata transmission rates of intermediate level however with broadercommunication ranges, are suitable for home networks or wireless LANs(Local Area Network) for the outdoor use. However, since terminals otherthan those for the wireless LAN can use the 2.4 GHz bandwidth, theguarantee of communication is low as, for example, communication cannotbe provided even for short-distance, depending on the wirelessenvironment. On the other hand, as the IEEE802.11a standard uses a 5-GHzbandwidth (details in bandwidths depending on countries) requiringcarrier sensing, the communication guarantee is higher at a shortdistance. However, because the used bandwidth is higher than 2.4 GHz,the communicable area is narrower than the LAN using 2.4 GHz bandwidthat the same transmission power. The UWB is defined as a wirelesscommunication standard having spectrum bandwidth of 500 MHz or higher at1.9 GHz to 10 GHz, for example, thus opening the prospective ofpermitting realizing rates of a few Gbps at distances within 10 m. A fordistances longer than 10 m, such wireless communication currentlypresents obstacles as for short distances the data transmission ratesare high while the transmission range becomes considerably narrow.

Hereafter, optical cables are expected to enter respective homes, andthus if it is assumed that home networks is provided with the wirelessnetworks, increase in transmission speed is be required. Accordingly ahigher transmission rate (speed) than that provided with the currentlyavailable wireless networks is required. For example, if a communicationstandard called 100Base-T is used, and then the wireless transmission ofdata is transmitted according to the standard, this is sufficientlypossible by using two bandwidths in the IEEE802.11g standard or theIEEE802.11a standard and, further, the UWB also presents no problem inthis case. However, if a high speed transmission is executed using thesemethods, there is a certain probability of instability to occur as thegain margin of the wireless link is not large, so that a stable wirelessnetwork cannot be provided for exclusively peer to peer communications.Thus, a stable wireless network can be provided only upon having arelayed network provided. Here, an internal structure of a relayterminal station capable of relayed communication is shown in FIG. 8.

Basically, almost all of functional blocks in the schematic diagram areequivalent to those in the base station and terminal station shown inFIG. 7. The different functional block is only the routing table 51. Therouting table is a table in which details for executing a change ofdestination of a packet (rewriting process of an MAC header) is writtenif the received packet is one for relaying. The process using therouting table 51 will be described later.

The structure of the relay communication station will be described withreference to FIG. 8. An antenna 31 is connected to an RF section 32. Thereception signal processed at the RF section 32 is successively suppliedto an analog/digital converter 33, a window detection section 34, a fastFourier transform section 35, a demodulation section 36, ade-interleaver 37, a Viterbi decoder 38, a reception data processingsection 39, and the data extracted and processed by the reception dataprocessing section 39 is supplied to a memory 40 to be accumulated.

Out of the reception data accumulated in the memory 40, the centralcontrol unit 41 separates the data directed to this communicationstation into various types of data such as the data suitable forrespective applications and image data to output the separated data.Further, the data relayed by this communication station is supplied to atransmission side memory 43 to be accumulated. The accumulated data inthe memory 43 is wirelessly transmitted by a processing structuresimilar to the transmission processing structure at the base station 10shown in FIG. 7. In other words, the transmission data accumulated inthe memory 43 is supplied to the transmission data processing section 44to execute the MAC process for transmission to provide packet-formatteddata. The packet data obtained by the transmission data processingsection 44 is subjected to the convolution coding process at aconvolution section 45, the interleaving coded bit strings at aninterleaver 46, the modulation such as the QPSK modulation at amodulation section 47, and the inverse fast Fourier transform processingand the window processing at an inverse fast Fourier transform section48 and is supplied to a digital•analog converter 49 to be converted intoan analog signal. The converted analog signal is supplied to an RFsection 32 to be subjected to analog processes such as filtering andfrequency conversion, to wirelessly transmit the frequency-convertedsignal at the connected antenna 31.

Further, to the central control unit 41, a timing control section 42 isconnected. Under the control by the central control unit 41, the timingcontrol section 42 instructs the reception timings and a signalprocessing method of respective circuits. In addition, the transmissiontimings, the demodulation method or the like at the circuits from thetransmission data processing section 44 to the RF section 32 are alsoset in accordance with the instruction from the timing control section42.

In addition, to the central control unit 41 a routing table 51 isconnected. If the received packet is a packet for relay, it constitutesa table in which details for executing change of the transmissiondestination of the packet (MAC header rewriting process). Morespecifically, as the details of the routing table 51, transmissionsource IDs and transmission destination IDs are formed in the tablecorresponding to one another one by one. The central control unit 41reads out the transmission source ID and then, picks up theto-be-transmitted ID from this table to rewrite the MAC header andtransfers it to a transmission processing buffer.

In the case of the conventional wireless relay terminal station as shownin FIG. 8, since the transmission rate is not so high, generally, therewiring of the MAC header is executed by software. In this case, thecentral control unit sends all the received packets to the memorycontrolled by the central control unit (in FIG. 8, the memory is omittedbecause it is an internal part of the central control unit) irrespectiveof whether the packet is directed to this station or directed to anotherstation and changes the MAC header using the routing table by thesoftware process at the central control unit if it is a packet toanother station.

In Japanese Laid-open patent application No. 7-121455, there is adescription of such a type of relay apparatus. However, the relayapparatus described in such applications an example in which relaying iscarried out using a wired network.

In order to provide a stable high speed wireless network, the process ofrewriting or the like for the MAC header should be executed not at theupper layer, but at the lower layer (the PHY layer, the MAC layer).However, in the case of the wireless communication, since it iscontrolled by the access method that is more complicated than that forthe wired communication, it requires the structure that is morecomplicated than the architecture of the relay apparatus used in thewired communication. For example, there is a large difference betweenthe wired communication and the wireless communication in that the datareceiving side should return a transmission acknowledge (ACK) at the MAClayer or the DLC layer.

The process for returning an ACK in response to the received data isconventionally done by judgment of the received data at the centralcontrol unit and by generating an ACK packet based on the control of thecentral control unit to transmit it, which is a large load of theprocess and as a factor impeding increasing the process. Upon executionof relaying process, the control unit determines the content of thereceived data also for the transmission process of the data to berelayed to execute the transmission process to the transmissiondestination, which shows a serious issue of excessive load to thecentral control unit as the control means of communication.

Further, in the case of the wireless communication, it is possible thatthe user receives the packet within the area where the radio wave canreach, however within an area where he/she does not wish to receive thedata. Thus, the wireless communication requires a securitycountermeasure. However, the execution of the process regarding securityat an upper layer extends the relay processing time, so that thethroughput decreases.

In consideration of those points, a preferred embodiment of the presentinvention aims at executing the relaying process for the wirelesscommunication through a high speed however simple control.

According to a preferred embodiment of the present invention, iftransmission and reception is executed with relaying a specified packetwithin wirelessly transmitted data, a header of the received packet isrecognized, a destination of the received data is determined based onthe recognized header, if the determined destination is not one's ownstation, the next transmission destination is recognized by looking up apredetermined table, based on the header recognition and thetransmission destination recognition, the packet to be relayed isdetermined, and a packet to be transmitted is selected between thepacket determined to be relayed and a packet that an application ofone's own station transmits.

Such structure enables to determine which packet is required to berelayed based on the recognition process of the header of the receivedpacket to transmit the determined packet, providing the wireless relaytransmission without intervention such as a central control unit.

According to a the preferred embodiments of the present invention,discrimination is made between a packet of (a user's) one's own stationand a packet for relay (relay packet), and the processing for the casethat the packet is for relay is executed without intervention by acontrol means such as a central control unit and the like, so that it ispossible to construct a wireless network executing the relay processingat a high speed. Further, the complicated process regardingretransmission is executed without a controlling means such as thecentral control unit to provide a stable wireless network. In addition,the routing table for the relay processing is constantly updated to addto the table the information of the packets of which processes are notexecuted, to eventually suppress unnecessary processes.

In this case, processing only the packets from the other stationsspecified using the security information excludes the packets of whichreceiving processing is not required, in order to provide acountermeasure against harmful behavior intending to decrease theperformance of the wireless network as a whole.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects and features of a preferred embodiment ofthe present invention will become more readily apparent to those ofordinary skill in the art from the following detailed description takenin conjunction with the accompanying drawings in which:

FIG. 1 is block diagram illustrating a structural example of a main partof a wireless communication apparatus according to an embodiment of apreferred embodiment of the present invention;

FIG. 2 is an illustration describing an example of a packet structureaccording to a preferred embodiment of the present invention;

FIG. 3 is an illustration describing an example of a queue tableaccording to a preferred embodiment of the present invention;

FIG. 4 is a flow chart illustrating an example of a sequence numbermanagement process according to an embodiment of a preferred embodimentof the present invention;

FIG. 5 is a flow chart describing an example of process for the case inwhich the communication environment for transfer destination is bad,according to a preferred embodiment of the present invention;

FIG. 6 is a block diagram illustrating a structural example of a mainportion of the wireless communication terminal apparatus according toanother preferred embodiment of the present invention;

FIG. 7 is a block diagram illustrating an example of conventionalwireless transmission and reception structure; and

FIG. 8 is a block diagram illustrating a structural example of aconventional wireless communication terminal apparatus.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE PRESENTINVENTION

Hereinafter, preferred embodiments of the present invention will bedescribed with reference to FIG. 1 to FIG. 4.

FIG. 1 is a schematic diagram illustrating a main part of the systemstructural example of this example. This FIG. 1 shows the processingstructure after the Viterbi decoder (corresponding to Viterbi decoder 38in FIG. 8), before the convolution section in the transmission system(corresponding to 45 in FIG. 8). For the structure from the RF sectionto the Viterbi decoder in the reception system, and the structure fromthe convolution section to the RF section in the transmission system,the structure having the same structure shown in FIG. 8 is applicable.

The structure shown in FIG. 1 will be described. The receptioninformation bit strings obtained by Viterbi decoding at the Viterbidecoder 101 are supplied to a reception data processing section 102. Thereception data processing section 102 carries out a reception processingin the MAC layer for extracting necessary data and if necessary, anerror correction process based on error correction codes. The processeddata is supplied to a packet control section 103.

The packet control section 103 determines the MAC header of the receivedpacket to determine the transmission destination. More specifically, ifthe transmission ID of the received packet is directed to this station,the packet control section 103 transmits it to the central control unit107 via the reception memory 104. If the transmission source ID isdirected to another station, the packet control section 103 determineswhether the ID exists in the routing table 105. If the ID exits, it istransmitted to the reception memory 104. If no ID, the packet isdeleted. If the packet is directed to another packet, the centralcontrol unit 107 is not informed of the reception of the packet.Alternatively, the packet stream control section 106, which controls thetransmission data as Queue (Queue), is informed that it is written inthe reception memory 104. The packet directed to this station, writtenin the reception memory 104 is transmitted to the upper layer via thecentral control unit 107.

The packet control section 106 is a circuit for managing thetransmission data as a queue and is controlled for each transmissiondestination ID.

Further, the packet transmitted from this terminal apparatus is held inthe transmission memory 109 under the control of the central controlunit 107, and the data held data is sent to a transmission processingsection 110 via a transmission selector 112. The transmission selector112 is a circuit for selecting either of the packet from the upper layervia the central control unit 107 or the packet transmitted from thememory 104, which packet is determined to be relayed by the packetcontrol section 103, based on the queue information managed by thepacket stream control section 106 and the information from the timingcontrol section 108 for controlling the transmission. Further, thetransmission selector 112 also has a function transmitting to thetransmission processing section 110 an acknowledge packet (ACK packet)for the packets directed to this station or other stations (only IDswritten in the routing table 105) in the packet control section 103. TheACK packet is previously prepared, for example, in the transmissionselector 112 and receives the transmission destination ID information atthe transmission timing (actually at a previous timing by a transmissionprocess interval to execute the wireless transmission at thetransmission timing) from the timing control section 108.

The transmission selector 112 is triggered in response to the IDinformation to acquire from the packet stream control section 106 theinformation indicative of where the data to be transmitted exists. Anexample of a format of the queue table managed within the packet streamcontrol section 106 is shown in FIG. 3. For example, if a datatransmission request for a transmission destination ID=0x03 is receivedfrom the timing control section 108, the transmission selector 112 firstreads the twelfth data stored in the reception memory 104 in accordancewith the queue table shown in FIG. 3, and an address of an MAC header isrewritten in accordance with the routing table 105, and then, the packetis forwarded to the transmission processing section 110.

After transfer, if there is a right of transmission to the transmissiondestination ID=0x03, the thirteenth packet in the transmission memory109 is read and forwarded to the transmission processing section 110.Here, either of the packets received from the upper layer in which anMAC header is added or the packet to which no MAC header is added can beforwarded. If the packet is one to which no MAC header is added, an MACheader is added in the transmission selector 112. The packet transmittedfrom the upper layer (i.e., not the packet to be relayed, but the packetto be transmitted from one's own station) is not subjected to rewritingthe MAC header. The packet with the header prepared by the transmissionselector 112 is forwarded to the transmission processing section 110.

A structural example of the packet wirelessly transmitted by thewireless communication system of this example will be illustrated inFIG. 2. As the MAC header, regions of a packet type, a packet datalength, a transmission destination address, a transmission sourceaddress, security information, and destination address of data areprepared. Then, data is arranged as payload and finally, CRC (CyclicRedundancy Check) codes are arranged as error correction codes. Thepacket structure shown in FIG. 2 is only an example, and thus, the orderof arrangement of the regions can be different. Also, other regionsmight be arranged.

Now turning back to FIG. 1, in this example, a security table 113 isprepared. The security table 113 is a table storing security informationfor determining whether the packet is received from a terminal (aharmful terminal) other than specified terminals against harmfulbehavior intending to reduce the performance of the whole of thewireless network by transmitting unnecessary packets. The security table113 accumulates security information operated from the information at apredetermined region, and upon reception of a packet directed to anotherperson, first it is determined whether it is allowed as a terminal ofone's own network. As a specific process for judgment, in thisembodiment, as shown in FIG. 2, the region having the securityinformation is prepared in the packet format. A transmission sourcetransmits the security information to a transmission destination as apart of data. As the predetermined regions, here, the transmissiondestination MAC address and the transmission source MAC address areused.

At first, it is assumed that the terminal added to the network as (theuser's) one's own station has a key specific to each terminal. This iscalled a common key. Thus, a station joined to one's own network atleast has keys for terminals at a radio-wave reachable area from itsposition. A transmission source terminal trying to transmit a packetencrypts the transmission destination MAC address and the transmissionsource MAC address with the common keys and adds it as the securityinformation to the data as a part of the data to generate and transmitthe packet.

On the other hand, the transmission destination having received thepacket decrypts the security information from the information of thetransmission destination address and the transmission source addressusing the previously given (by secure communication) common key of thetransmission source. Next, it is determined whether the decryptionresult agrees with the security information received as a part of thedata. If no agreement, the received packet is not forwarded to thetransmission selector 112, and also no ACK packet is transmitted.

The execution of the process in the communication terminal apparatushaving the structure as described above, upon reception of a packetnecessary for relaying among the packets received by this communicationterminal apparatus, the communication terminal apparatus directly sendsthe packet from the reception memory 104 to the transmission selector112, which rewrites the address in the MAC header therein to execute thetransmission process. Thus, the central control unit 107 does notintervene in relay-transmission, so that a high speed processing isprovided. Further, execution of the process of the security informationusing the security table 113 excludes the packets of which receptionprocessing by this communication terminal apparatus is unnecessaryagainst the harmful behavior intending to decrease the performance ofthe whole of the wireless network.

The structure of the wireless communication terminal is not limited tothe structure shown in FIG. 1. For example, it is also possible that thearrangement of the packet control section 103 and the reception memory104 is inversed in order and then, the received packet is once stored inthe reception memory to execute the process at the packet controlsection. Further, the reception memory 104 and the retransmission memory109 may be physically structured with one memory. Still further, theprocess (addition or rewriting a header) regarding the MAC headerexecuted by the transmission selector 112 can be executed by thetransmission process section 110. In addition, in the transmissionselector 112, the process for providing security is not limited to theabove-described process. For example, other security methods such as theWEP and the like are applicable. Further, the predetermined regionsnecessary for execution of the security process are the transmissiondestination MAC address and the transmission source MAC address.However, they may not be the MAC addresses, but other data such as ID orthe like identifiable for the terminal. In addition, previouslyacquiring the security information based on combination of transmissionsource addresses and transmission destination addresses providestransfer at a shortened operation interval.

Next, an example of communication operation at the wireless terminalapparatus having the structure as described above will be described withreference to the flow chart in FIG. 4. In the wireless communication, itis general that the judgment as to whether retransmission should beexecuted in accordance with the transmission confirmation with the ACKis carried out at the MAC layer or the DLC layer. The judgment as towhether it reaches the transmission destination is made using thesequence number and the ACK inserted in the MAC header. FIG. 4 shows anexample of the operation using these sequence number and the ACK.

Hereinafter, description is made based on the flow chart in FIG. 4. Atfirst, in step S10, the reception process section 102 receives a packet.In step S11, the security check is executed using the stored data in thesecurity table 113. Next, the sequence number written in the MAC headeradded to the received packet directed to one's own station is insertedinto an ACK packet to transmit the ACK packet, in step S12. The packetcontrol section 103, the transmission selector 112, and the transmissionprocess section 110 execute the process for transmission after insertingthe sequence number into the ACK packet.

Next, the packet control section 103 determines whether the receivedpacket is directed to one's own station, in step S13. If the packet isdirected to one's own station, the packet is stored in the receptionmemory 104, in step S14. Further, upper layers are informed of receptionof the packet via the central control unit 107, in step S15. The centralcontrol unit 107 or the upper layers forwards the content stored in thereception memory 104 to a memory of the upper layer, in step S16. Thepacket control section 103 and the central control unit 107 execute thisprocess.

Further, in step S13, if the packet is not directed to one's ownstation, the processing proceeds to step S17, where the packet controlsection 103 searches the routing table 105 to determine whether thepacket is to be routed. After this, the packet control section 103confirms whether the received transmission source ID exists in therouting table, in step S18. If an ID exists, the processing proceeds tostep S19, in which is referred the sequence table on which a maximumsequence number is written for each ID to confirm whether it is not apacket that have been received. If the packet that has been received,the processing does not proceed to steps of S20 and beyond.

Next, the received packet is stored in the reception memory 104, in stepS20. The packet control section 103 informs the packet stream controlsection 106 of the reception of the packet to be routed, in step S21. Ifthe timing control section 108 transmits the to-be-routed packet at atransmission timing, the transmission selector 112 writes on the MACheader the sequence number for transmission source ID determined by therouting table 105 (obtained by adding one thereto because the numberthat has been received is written in the sequence table 105) to add itto the data, in step S22. The packet generated as mentioned above isprocessed and transmitted at the transmission processing section 110, instep S23.

Further, in step S18, if there is no transmission source ID in therouting table, the packet control section 103 executes a processdeleting the corresponding packet, in step S24.

In the case where the wireless communication is carried out withtransmission of the ACK packets as described above, as the process forthe case that the circumstance of communication with the packetdestination is bad, the process shown in the flow chart in FIG. 5 may beused. In other words, the number of times of re-transmission from thecorresponding other station is confirmed, in step S31. It is determinedwhether the number of times of retransmission exceeds a predeterminednumber of times (for example, ten times), in step S32. If the number oftimes exceeds the predetermined number of times, an NACK packet isreturned to the transmission source indicating inability of reception,in step S33.

Further, in the flow chart in FIG. 4, as an additional process in thestep S17, for example, a process may be added to inform the centralcontrol unit 107 of the ID of the packet newly received. The informed IDis used as information for renewing the routing table 105. In addition,though a terminal is near the station, it may be connected to anothernetwork, and thus the term “delete” may be added, in order not to informthe central control unit 107 of the packet received from a terminal ofother network every time, like the transmission ID=0x4. Further, it isalso possible to have an ID for each use. For example, in the systemhaving first data having a strong real time feature, second datarequiring no real time characteristic, and third data for controlling awireless line, separate IDs may be assigned to the first and seconddata. No ID is assigned to the third data, and thus, if a packet isreceived, an ACK is immediately sent back.

In the above-described example, the description was made with assumptionthat the received sequence number is written in the sequence table.However, it may be a sequence for transmission. Still further, therewriting and addition process of the MAC header in step S22 may beexecuted at the transmission processing section 110.

Further, in the description above, the description was made as anapparatus connected to one wireless method of network. However, it maybe an apparatus connected to a wireless network having a plurality oftypes of wireless methods or standards.

For example, it is assumed that a terminal is equipped with theIEEE802.11a system and the IEEE802.11b system. Since the IEEE802.11asystem may not be capable of communication at the distance that allowsthe IEEE802.11b system to execute a peer to peer communication, the useof the IEEE802.11a system, as an alternative path for the IEEE802.11asystem, requires preparing a relay apparatus for the IEEE802.11a toprovide reach with more than one hop. In other words, in thecircumstance in which communication is executed in the IEEE802.11bsystem, the use of the wireless network assuming the use of relayapparatuses can continue the communication in the IEEE802.11a systemthough a microwave oven, which may generate interference waves, isturned on.

FIG. 6 shows a structural example of a wireless communication terminalconnected to such a wireless network using a plurality of wirelesssystems. In FIG. 6, the receiving and control systems are basically thesame as those in structure shown in FIG. 1, and thus the correspondingblocks are designated with the same references. Further in FIG. 6, twosets of transmission systems are connected to the transmission selector112 in the transmission system. In other words, the first transmissionsystem includes a first transmission processing section 201 and aconvolution section 202 for convolution-coding the signal processed bythe transmission processing section 201 to wirelessly transmit theoutput of the convolution section 202 with a known transmission processsystem. This first transmission system assumes the IEEE802.11a system.The second transmission system includes a second transmission processingsection 203 and a modulation section 204 for modulating the signalprocessed by the transmission processing section 203 to wirelesslytransmit the output of the modulation section 204 with a knowntransmission process system. The second transmission system assumes theIEEE802.11b system. The routing table 105, the packet stream controlsection 106, and the timing control section 108 are set to control twosystems. Further the transmission selector 112 is set to provide a finaljudgment whether the wireless transmission is to be executed with thefirst transmission system or the second transmission system. Forexample, according to the instruction from the timing control section108 for both, if the right of transmission in the wireless communicationsystem adopting the first transmission system is not established, butthe right of transmission can be established in the wirelesscommunication system adopting the second transmission system, the secondtransmission system executes the transmission process.

Further, FIG. 6 shows a structure in which only the transmission systemadopts two communication systems. However, it is also possible to makethe structure capable of receiving signals of two communication systems.

In addition, for the case that a transmission system circuit includingtwo wireless communication systems is provided, the two wirelesscommunication systems are not limited to wireless communicationapparatuses equipped with the IEEE802.11a and IEEE802.11b systems. Forexample, it is also provided with combinations of IEEE802.11a standard,the IEEE802.11b standard, the Bluetooth (trade mark) standard, theIEEE802.11g standard, the UWB standard and the like. Further, the numberin combination of standards is not limited to two, but may be more thanone.

Still further, the judgment or determination at the transmissionselector as to which wireless system is used is not limited to theabove-described process. For example, it is also possible to determinewhich one should be selected in accordance with the SN ratio, the errorrate, the throughput and the like, of the reception signal.

It is therefore to be noted that the preferred embodiments of thepresent invention are not limited to the above-mentioned examples ofpreferred embodiments, so that examples of preferred embodiments of thepresent invention and equivalents thereof may be appropriately modified,combined, sub-combined, etc., to be implemented within the scope and thespirit of the invention.

What is claimed is:
 1. A wireless communication method for performingtransmission and reception while relaying a packet within wirelesslytransmitted data, the method comprising the steps of: identifying aheader of the received packet; determining a destination of the receiveddata based on the recognized header; recognizing a next transmissiondestination by looking up a table, if the determined destination is notone's own station; determining a packet to be relayed based on therecognition of said header and the recognition of said transmissiondestination; selecting from said packets determined to be relayed, apacket to be transmitted among packets to be transmitted between packetsto be transmitted by an application of one's own station; andtransmitting the selected packet.
 2. The wireless communication methodas claimed in claim 1, wherein the wireless communication methodtransmits a reception completion confirmation packet to the packettransmission source if the received and determined-packet to be relayedhas no error.
 3. The wireless communication method as claimed in claim1, further comprising the steps of: discriminating sequence numbers ofthe packets determined to be relayed and the packets to be transmittedby an application of one's own station; managing the discriminatedsequence numbers; and if the received packet is a renewing the sequencenumber, transmitting a reception completion confirmation packet intowhich the renewing sequence number is inserted.
 4. The wirelesscommunication method as claimed in claim 1 further comprising the stepsof: selecting a method of communication and transmitting a packet underthe selected method of communication, if relaying is possible under morethan one method of communication.
 5. The wireless communication methodas claimed in claim 1, wherein: the process of transmission of packetand the process of transmission of the reception completion confirmationpacket are not performed if the packet is from a station from whichpacket reception is not required, according to determination accordingto security information included in the received packet and a securitytable.
 6. A wireless communication apparatus for performing transmissionand reception while relaying a packet within wirelessly transmitteddata, the apparatus comprising: reception unit for receiving wirelesslytransmitted data; header recognition section for recognizing a headerincluded in the data received by the reception unit; one's own-stationpacket determining section for determining whether the data received bythe reception unit is directed to one's own station; table forrecognizing a next transmission destination based on the destination ofthe data received by the reception unit; relay station packetdetermining section for determining a packet to be relayed through thetable and the header recognition section; storage unit for temporarilystoring the transmission packet from an application of one's ownstation; transmission packet selection unit for selecting either thepacket stored in the storage unit or the packet determined by the relaystation packet determining section; and transmission unit for wirelesslytransmitting the packet selected by the transmission packet selectingsection.
 7. The wireless communication apparatus as claimed in claim 6,wherein the transmission unit of the wireless communication apparatustransmits a reception completion confirmation packet to the transmissionsource of the packet if the packet to be relayed, received by thereception unit and determined by the relay station packet determiningsection, has no data error.
 8. The wireless communication apparatus asclaimed in claim 6, further comprising: sequence number managementsection for determining the sequence numbers of the packet to be relayedreceived by the reception unit and the packet determined by the one'sown-station packet determining section and managing the determinedsequence numbers; wherein a reception completion confirmation packetinto which an updated sequence number is inserted is transmitted by thetransmission unit, if the sequence number management section detectswhether the received packet is one in which sequence number is to beupdated.
 9. The wireless communication apparatus as claimed in claim 6,further comprising: first transmission unit according to a first methodof communication; and second transmission unit according to a secondmethod of communication; wherein a packet is transmitted upon selectionof either the first or the second transmission unit based on thetransmission destination determined by the relay packet determiningsection.
 10. The wireless communication apparatus as claimed in claim 6,further comprising a table for storing security data for recognition ofa communication counterpart; wherein the header recognition sectionneither transmits the corresponding packet from the transmission unitnor a reception completion confirmation packet, if the packet is from astation from which packet reception is not required as determined by thesecurity information included in the received packet and informationstored in the security table.
 11. The wireless communication apparatusas claimed in claim 6, further comprising a packet data processingsection for processing a packet if the one's own-station packetdetermining section determines that the packet is the packet of one'sown-station.